下面是我将要测试的方法，我希望IsPhoneNomValid（）返回false，这样我就可以Assert我的期望值：

public async Task<UserResponseDto> RegisterUser(RegistrationRequestDto register, CancellationToken cancelationToken)
    {
        // I want the IsPhoneNomValid() method, Would return "FALSE"
        var isPhoneNumberValid = register.PhoneNumber.IsPhoneNomValid();

        if (!isPhoneNumberValid)
            return new UserResponseDto
            {
                Status = new StatusMaker().ErrorStatus("Some Error Message")
            };

        var isActiveAccountPhoneNumberExists = await IsActiveAccountPhoneNumberExist(register.PhoneNumber, cancelationToken);

        if (isActiveAccountPhoneNumberExists.Status == "error")
            return new UserResponseDto
            {
                Status = isActiveAccountPhoneNumberExists
            };

       

    }

RegisterUser_MustReturnPhoneNumberError是我的测试方法：

public class AccountUserTests
{

    private Mock<IUserService> _userService { get; set; }

    public AccountUserTests()
    {
        _userService = new Mock<IUserService>();
    }

    public async Task RegisterUser_MustReturnPhoneNumberError()
    {
        //Arrang

        // in here I want to setup IsPhoneNomValid() would return false.

        //Act

        //Assert
    }
}

有什么方法可以测试我正在测试的主函数中使用的静态方法吗？
下面是IsPhoneNomValid（）代码：

public static class Validation
{
    public static bool IsPhoneNomValid(this string phoneNumber)
    {
        //TODO Does it need to be foreign phone numbers ?
        var isMatch = Regex.Match(phoneNumber, @"^09[0-9]{9}$");

        if (isMatch.Success)
            return true;

        return false;
    }
}